This invention relates in general to breathing masks and in particular to a new and useful device for testing the sealing capability of the mask.
The tight fit of oxygen masks is at least as important as the purely technical operation as far as the efficiency of the respirator is concerned. The efficiency is limited in practice more by an insufficiently tight fit of the oxygen mask and the tight connection of the respirator than by operational failure or other possible leakages.
A known device for testing the tight fit of oxygen masks on the wearer contains as an essential part a hood of transparent material, for example, plastic sheet. It has an expiration air connection tightly traversing the material of the hood, which can be connected to the expiration valve of the mask, with a receiver for gas testing tubes. In another opening of the hood, material is arranged, the nipple of the oxygen mask for the filter, and the ventilating air supply, from a respirator is sealed by means of a gasket. The hood is tightly sealed from the surrounding atmosphere by a collar around the neck of the mask wearer. The test gas is introduced into the hood through another tight connection. In order to test the tightness of the oxygen mask, the hood is filled with test gas. In case of leakage, it penetrates into the interior of the mask during respiration. It mixes there with the ventilating air sucked in by the wearer. During its passage, it can be tested by means of the gas testing device, e.g. a testing tube for determining the gas type and thus also the tightness or untightness. A disadvantage of this testing device is the requirement for a time-consuming attachment of the hood and the impossibility of checking an important leakage point, namely, the connection of the ventilating air supply from the respirator (DAS No. 26 51 217).
Another known device for testing the tightness of oxygen masks on the wearer consists of a hood terminating on the body, with an additional tight-fitting inner hood. The inner hood is connected over a line to a test gas source. The test gas enters the inner hood, passes through it and flows then off over the outer hood terminating on the body through an exhaust to the outside. The interior of the mask between the oxygen mask and the covered portions of the head of the wearer is connected over a connection line to a test gas meter which measures directly the test gas concentrations in the interior of the mask, hence a possible leakage in the seal and/or other leakages. This device is complicated because of the two hoods with the difficult handling of the inner hood. The testing procedure is time-consuming; the test gas consumption is high (DAS No. 26 52 136).